Puerto Montt, Chile
Puerto Montt, Chile

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Marin S.L.,Austral University of Chile | Ibarra R.,Instituto Tecnologico del Salmon | Medina M.H.,Instituto Tecnologico del Salmon | Jansen P.A.,Norwegian Veterinary Institute
Preventive Veterinary Medicine | Year: 2015

The variety of antiparasitics that can be used against caligid copepods is limited and efforts are needed to maintain their efficacies. The objective of this study was to monitor the sensitivity of Caligus rogercresseyi, populations towards antiparasitics based on deltamethrin, cypermethrin and azamethiphos within and across geographic regions. The bioassay design consisted of exposing parasites collected from 23 farms to the different chemotherapeutants at the concentration and exposure times recommended for field treatment, under laboratory conditions, and evaluating the number of dead and live parasites 48. h after exposure. Parasites were collected from 23 farms distributed in four macrozones in the Los Lagos region and three macrozones in the Aysén region. Parasite sensitivity was evaluated using a Generalized Linear Mixed Model of the Binomial family (Logit) fit by the maximum likelihood, using the lme4 package in R. Parasite gender, macrozone, and antiparasitics were used as fixed factors and farm was the random factor. The model including all the factors proved to be a useful tool for predicting parasite sensitivity. This approach identified (i) those macrozones with a greater likelihood of finding parasite populations which are more or less sensitive to the three antiparasitics, (ii) cases in which parasite sensitivity to the different antiparasitics varied within a given macrozone, (iii) differences in sensitivity between females and males and (iv) an important random effect associated with farm. The results indicate a spatial variability of parasite sensitivity to antiparasitics which, added to the continuous treatments applied on farms, suggest it is necessary to regularly update the sensitivity status in the macrozones. This would allow managers to improve their decision making processes regarding the type of antiparasitic to be used in a given situation. The one-concentration type bioassay performed in this study allowed us to perform a large spatial study with replicated tests of the sensitivity of C. rogercresseyi to pyrethroids and azamethiphos. Further studies should focus on the farm effects, the relationship between the sensitivity of parasites and field efficacy, as well as parasite population structure and connectivity with regard to parasite transmission between farms. © 2015 Elsevier B.V..


Kristoffersen A.B.,National Veterinary Institute | Kristoffersen A.B.,University of Oslo | Rees E.E.,University of Prince Edward Island | Stryhn H.,University of Prince Edward Island | And 4 more authors.
Preventive Veterinary Medicine | Year: 2013

The decline of fisheries over recent decades and a growing human population has coincided with an increase in aquaculture production. As farmed fish densities increase, so have their rates of infectious diseases, as predicted by the theory of density-dependent disease transmission. One of the pathogen that has increased with the growth of salmon farming is sea lice. Effective management of this pathogen requires an understanding of the spatial scale of transmission. We used a two-part multi-scale model to account for the zero-inflated data observed in weekly sea lice abundance levels on rainbow trout and Atlantic salmon farms in Chile, and to assess internal (farm) and external (regional) sources of sea lice infection. We observed that the level of juvenile sea lice was higher on farms that were closer to processing plants with fish holding facilities. Further, evidence for sea lice exposure from the surrounding area was supported by a strong positive correlation between the level of juvenile sea lice on a farm and the number of gravid females on neighboring farms within 30. km two weeks prior. The relationship between external sources of sea lice from neighboring farms and juvenile sea lice on a farm was one of the strongest detected in our multivariable model. Our findings suggest that the management of sea lice should be coordinated between farms and should include all farms and processing plants with holding facilities within a relatively large geographic area. Understanding the contribution of pathogens on a farm from different sources is an important step in developing effective control strategies. © 2013 .


PubMed | Norwegian Veterinary Institute, Austral University of Chile and Instituto Tecnologico del Salmon
Type: Journal Article | Journal: Preventive veterinary medicine | Year: 2015

The variety of antiparasitics that can be used against caligid copepods is limited and efforts are needed to maintain their efficacies. The objective of this study was to monitor the sensitivity of Caligus rogercresseyi, populations towards antiparasitics based on deltamethrin, cypermethrin and azamethiphos within and across geographic regions. The bioassay design consisted of exposing parasites collected from 23 farms to the different chemotherapeutants at the concentration and exposure times recommended for field treatment, under laboratory conditions, and evaluating the number of dead and live parasites 48h after exposure. Parasites were collected from 23 farms distributed in four macrozones in the Los Lagos region and three macrozones in the Aysn region. Parasite sensitivity was evaluated using a Generalized Linear Mixed Model of the Binomial family (Logit) fit by the maximum likelihood, using the lme4 package in R. Parasite gender, macrozone, and antiparasitics were used as fixed factors and farm was the random factor. The model including all the factors proved to be a useful tool for predicting parasite sensitivity. This approach identified (i) those macrozones with a greater likelihood of finding parasite populations which are more or less sensitive to the three antiparasitics, (ii) cases in which parasite sensitivity to the different antiparasitics varied within a given macrozone, (iii) differences in sensitivity between females and males and (iv) an important random effect associated with farm. The results indicate a spatial variability of parasite sensitivity to antiparasitics which, added to the continuous treatments applied on farms, suggest it is necessary to regularly update the sensitivity status in the macrozones. This would allow managers to improve their decision making processes regarding the type of antiparasitic to be used in a given situation. The one-concentration type bioassay performed in this study allowed us to perform a large spatial study with replicated tests of the sensitivity of C. rogercresseyi to pyrethroids and azamethiphos. Further studies should focus on the farm effects, the relationship between the sensitivity of parasites and field efficacy, as well as parasite population structure and connectivity with regard to parasite transmission between farms.


PubMed | Austral University of Chile, Instituto Tecnologico del Salmon, Sernapesca and U.S. Department of Agriculture
Type: | Journal: Preventive veterinary medicine | Year: 2016

Area management, the coordination of production and biosecurity practices across neighboring farms, is an important disease control strategy in aquaculture. Area management in aquaculture escalated in prominence in response to outbreaks of infectious salmon anemia (ISA) internationally. Successes in disease control have been attributed to the separation achieved through area-level synchronized stocking, fallowing, movement restrictions, and fomite or pest control. Area management, however, is costly; often demanding extra biosecurity, lengthy or inconveniently timed fallows, and localization of equipment, personnel, and services. Yet, this higher-order organizational structure has received limited epidemiologic attention. Chiles National Fisheries and Aquaculture Service instigated area management practices in response to the 2007 emergence of ISA virus (ISAV). Longitudinal data simultaneously collected allowed retrospective evaluation of the impact of component tenets on virus control. Spatiotemporal analyses identified hydrographic linkages, shared ports, and fish transfers from areas with recent occurrence of ISAV as the strongest predictors of virus spread between areas, though specifics varied by ISAV type (here categorized as HPR0 for the non-virulent genotypes, and HPRv otherwise). Hydrographic linkages were most predictive in the period before implementation of enhanced biosecurity and fallowing regulations, suggesting that viral load can impact spread dynamics. HPR0 arose late in the study period, so few HPRv events were available by which to explore the hypothesis of HPR0 as progenitor of outbreaks. However, spatiotemporal patterns in HPRv occurrence were predictive of subsequent patterns in HPR0 detection, suggesting a parallel, or dependent, means of spread. Better data precision, breadth and consistency, common challenges for retrospective studies, could improve model fit; and, for HPR0, specification of diagnostic test accuracy would improve interpretation.


PubMed | Salmones Camanchaca, Instituto Tecnologico del Salmon, San Sebastián University, Chile Ltda ADL Diagnostic and 5 more.
Type: Journal Article | Journal: Preventive veterinary medicine | Year: 2014

Aquaculture is anticipated to be a critical element in future solutions to global food shortage. However, diseases can impede industry efficiency and sustainability. Consequently, diseases can and have led to dramatic re-structuring in industry or regulatory practices. The emergence of infectious salmon anemia (ISA) in Chile is one such example. As in other countries, many mitigations were instituted universally, and many incurred considerable costs as they introduced a new layer of coordination of farming activities of marine sites within common geographic areas (termed neighborhoods or barrios). The aggregate response led to a strong reduction in ISA incidence and impact. However, the relative value of individual mitigations is less clear, especially where response policies were universally applied and retrospective analyses are missing controls (i.e., areas where a mitigation was not applied). Further, re-focusing policies around disease prevention following resolution of an outbreak is important to renew sustainable production; though, again, field data to guide this shift in purpose are often lacking. Expert panels can offer timely decision support in the absence of empirical data. We convened a panel of fish health experts to weight risk factors predictive of ISA virus (ISAV) introduction or spread between Atlantic salmon barrios in Chile. Barrios, rather than sites, were the unit of interest because many of the new mitigations operate at this level and few available studies examine their efficacy. Panelists identified barrio processing plant biosecurity, fallowing strategies, adult live fish transfers, fish and site density, smolt quality, hydrographic connection with other neighborhoods, presence of sea lice (Caligus rogercresseyi), and harvest vessel biosecurity as factors with the greatest predictive strength for ISAV virulent genotype (HPR-deleted) occurrence. Fewer factors were considered predictive of ISAV HPR0 genotype (HPR0) occurrence, with greatest strengths assigned to fish and site density, adult live fish transfers, and smolt facility HPR0 status. Field validation based on ISAV and risk factor occurrence after panel completion generally supports expert estimates, and highlights a few factors (e.g., broodstock HPR0 status) less conclusive in the original study. Results inform legislation, industry best management practices and surveillance design.


Vanderstichel R.,University of Prince Edward Island | St-Hilaire S.,University of Prince Edward Island | Ibarra R.,Instituto Tecnologico del Salmon | Lyngstad T.M.,Norwegian Veterinary Institute | And 2 more authors.
Aquaculture | Year: 2015

In 2007, Chile reported its first case of infectious salmon anemia (ISA), caused by ISA virus (ISAV), in sea-cage reared Atlantic salmon. By 2010, the ISA disease outbreak was under control, but similarly to other countries, Chile continues to occasionally detect the non-pathogenic variant of ISAV (HPR0 ISAV). The Chilean salmon industry has been including gill samples in their routine ISAV monitoring program to improve the detection of HRP0 ISAV, which provides an opportunity to better assess the distribution of HPR0 ISAV and describe its occurrence in the Chilean marine aquaculture industry.A risk and a relative risk surface map were generated for the predominant regions of the Chilean aquaculture industry, and demonstrated areas of increased risk to HPR0 ISAV for the entire surveillance period. The observed occurrence and seasonal patterns of HPR0 ISAV were similar to those previously reported in Chile and in other countries. Further, spatiotemporal cluster analysis showed that the areas with a high-risk of HPR0 ISAV changed during the surveillance period (highly prevalent and causing non-clinical transient infections), and cases in clusters were initially observed within companies, followed by neighboring farms affecting other companies.Monitoring HPR0 ISAV in marine phase salmon production highlighted possible transmission patterns within the Chilean aquaculture industry and identified higher-risk areas associated with circulating orthomyxoviruses. © 2014 Elsevier B.V.


Price D.,University of Prince Edward Island | Stryhn H.,University of Prince Edward Island | Sanchez J.,University of Prince Edward Island | Ibarra R.,Instituto Tecnologico del Salmon | And 2 more authors.
Diseases of Aquatic Organisms | Year: 2016

Piscirickettsiosis is the most prevalent salt-water infectious disease in farmed salmonids in Chile. Antimicrobials are used to treat this disease; however, there is growing concern about the poor response to therapeutants on some fish farms. The objective of this study was to assess whether factors such as type of antibiotic used, average fish weight, temperature at the beginning of the treatment, and mortality at the time of treatment administration affect the probability of treatment failure against piscirickettsiosis. Pen-level treatment and production information for the first treatment event from 2014 pens on 118 farms was used in a logistic mixed model to assess treatment failure. We defined a failed treatment as when the average mortality 3 wk after the treatment was above 0.1%. Farm and company were included in the model as random effects. We found that the antibiotic product, mortality level before the treatment, and fish weight at the start of the treatment all had a significant effect on treatment outcome. Our results suggest that antibiotic treatment success is higher if the treatment is administered when mortality associated with piscirickettsiosis is relatively low. We discuss the effect of weight on treatment success and its potential relationships with husbandry practices and drug pharmacokinetics. © Inter-Research 2016.


Arriagada G.A.,University of Prince Edward Island | Stryhn H.,University of Prince Edward Island | Campisto J.L.,Instituto Tecnologico del Salmon | Rees E.E.,University of Prince Edward Island | And 4 more authors.
Aquaculture | Year: 2014

Control of sea lice in Chile is largely based on antiparasitic treatments, synthetic pyrethroids being the most used drugs. In recent years, farmers in Chile have reported decreased performance of pyrethroid-based treatments. The aim of this study was to assess the performance of two deltamethrin-based (Alphamax® and a generic product) and one cypermethrin-based (Betamax®) product on the different life stages of Caligus rogercresseyi, while controlling potential confounders. We found that both deltamethrin products and the cypermethrin product had a significant effect on the reduction of juvenile, mobile adult, and gravid female lice, compared with untreated pens; however, the effect on juvenile lice was less than on mobile stages. There was no evidence that pyrethroids performed better on certain mobile life stages, such as gravid females. When the three products were compared, no significant differences were observed in the numbers of juvenile, adult male, and non-gravid female lice after we controlled for potential confounders; however, cypermethrin exhibited a small, yet significantly greater effect on the gravid female group when compared with one of the deltamethrin-based products. We also confirmed that other factors besides the product choice, such as the pre-treatment sea lice abundance, water temperature and salinity, and time elapsed to the post-treatment sample, affect the post-treatment sea lice level as well, and therefore, they should be taken into consideration when assessing the effect of immersion treatments. © 2014 Elsevier B.V.


Rees E.E.,University of Prince Edward Island | Ibarra R.,Instituto Tecnologico del Salmon | Medina M.,Instituto Tecnologico del Salmon | Sanchez J.,University of Prince Edward Island | And 4 more authors.
Aquaculture | Year: 2014

Salmon Rickettsia Syndrome (SRS), also known as Salmon Rickettsia Septicemia, caused by Piscirickettsia salmonis is the most common bacterial disease in the Chilean salmon aquaculture industry. The epidemiology of this pathogen is relatively unknown. Using the Chilean salmon aquaculture industry monthly diagnostic data collected between January 2009 and December 2012, we assessed the spatial and environmental factors associated with the reporting of SRS on Atlantic salmon, coho salmon, and rainbow trout farms. Crops of fish were on average 60% likely to report SRS during our study time period. The probability of a farm reporting SRS was positively associated with temperature, time in salt water, and the number of SRS infected neighbors. The distance effect from infected neighboring farms that best fit the model for predicting SRS on a farm varied by species but ranged between 7.5 and 10. km. Our study suggests reducing disease on farms will not only benefit the producer but also reduce the probability that P. salmonis is transferred to neighboring farms. © 2014 Elsevier B.V.


PubMed | University of Prince Edward Island, Analysis Inc. and Instituto Tecnologico del Salmon
Type: | Journal: Preventive veterinary medicine | Year: 2016

The sea louse is considered an important ectoparasite that affects farmed salmonids around the world. Sea lice control relies heavily on pharmacological treatments in several salmon-producing countries, including Chile. Among options for drug administration, immersion treatments represent the majority of antiparasitic control strategies used in Chile. As a topical procedure, immersion treatments do not induce a long lasting effect; therefore, re-infestation from neighbouring farms may undermine their efficacy. Synchronization of treatments has been proposed as a strategy to improve immersion treatment performance, but it has not been evaluated so far. Using a repeated-measures linear mixed-effect model, we evaluated the impact of treatment synchronization of neighbouring farms (within 10km seaway distance) on the adult lice mean abundance from weeks 2 to 8 post-treatment on rainbow trout and Atlantic salmon farms in Chile, while controlling for external and internal sources of lice before the treatments, and also for environmental and fish-related variables. Results indicate that treatment synchronization was significantly associated with lower adult lice levels from weeks 5 to 7 after treatment. This relationship appeared to be linear, suggesting that higher levels of synchronization may result in lower adult sea lice levels during these weeks. These findings suggest that synchronization can improve the performance of immersion delousing treatments by keeping sea lice levels low for a longer period of time. Our results may be applicable to other regions of the world where immersion treatments are widely used.

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